Washington, 15 April 2004 (RFE/RL) -- The United States government says it has advised Tehran that it would not be appropriate for Iran to try to mediate an end to the standoff between the U.S.-led coalition in Iraq and militant Shi'ite cleric Muqtada al-Sadr.

At the same time, State Department spokesman Richard Boucher told reporters today that Washington would be pleased if a delegation from Tehran now in Baghdad used its influence with the Shi'a community to promote the authority of the Iraqi interim administration.

Boucher said Iran should try to bring whatever influence it can that would help stabilize the situation in Iraq peacefully.

Meanwhile, the hostage crises continued in Iran today as militants released three Japanese hostages but executed an Italian, and the U.S. military reported that a few dozen foreign workers are either missing or captured.

An Iranian diplomat in was shot and killed today in Baghdad.

An audiotape purportedly made by Al-Qaeda leader Osama bin Laden aired on Arab television stations today, offered a truce to European nations that do not attack Muslim nations. The Central Intelligence Agency said the tape is probably authentic. Italy, Spain, Germany, Britain, and the European Union all rejected the offer.

In Samarra, a bomb killed a U.S. soldier today and wounded three others. Hospital officials in Al-Fallujah say U.S. tank and rifle fire killed three Iraqis.

Also, U.S. forces shelled and damaged Al-Fallujah's second-largest mosque. U.S. rules of engagement permit troops to attack mosques if they determine insurgents are using them as a base for attacks.